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ced4568andClaude Sonnet 5 e007bcf000 feat(root02): author Linux Administration & Networking

Adds all 6 ROOT 02 modules (Linux system administration, storage & filesystems, the
Networking Mental Model, Linux network inspection, DNS & HTTP, Linux troubleshooting) — 37
activities, each with a real lesson, demonstration/guided exercise, knowledge check, hands-on
Lab, and reflection. The Networking Mental Model module (M3) gets deliberately extra depth per
its "critical module" designation, with no lab by design — conceptual mastery via knowledge
check and guided exercise, matching root-05-m00's own precedent.

Adds 6 new hands-on Linux/networking scenarios plus 2 MCQs: linux-service-inspection (inspects
the platform's own real nginx without touching it — a genuinely safe, real service-inspection
target that avoids ever risking the Lab's own connectivity), linux-service-lifecycle (start/
verify/stop a fully controllable service), linux-storage-inspection, linux-network-inspection
(ip/ss/getent/curl, each framed as answering one specific diagnostic question),
linux-dns-http-diagnosis (a genuine DNS-resolves-but-wrong-port failure, diagnosed and fixed),
and linux-troubleshooting-framework (a real missing-config-file failure, resolved via the
RootNode Observe/Evidence/Hypothesis/Test/Repair/Validate/Prevent framework). All tested
end-to-end via the real scenario-validation API, including negative tests confirming they fail
when unsolved.

Wires rootnode-linux-networking-assessment (2 required + 4 random-draw scenarios) using the
existing Phase 3B assessment engine.

Co-Authored-By: Claude Sonnet 5 <[email protected]>

2026-08-26 17:07:46 -05:00

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Demonstration: Every Step, In Order, On a Real Failure

OBSERVE

A startup script fails: /srv/demo/start.sh exits with an error. That's the specific, concrete symptom — not "the service is down."

GATHER EVIDENCE

$ /srv/demo/start.sh
FATAL: config file not found: /srv/demo/config/settings.conf

The script's own error message IS the evidence — no guessing required.

FORM HYPOTHESIS

The config file at that exact path doesn't exist. That's the specific, testable hypothesis — not "something's misconfigured."

TEST

$ ls /srv/demo/config/
ls: cannot access '/srv/demo/config/': No such file or directory

Confirmed — the directory itself doesn't exist yet, not just the file.

REPAIR

$ mkdir -p /srv/demo/config
$ echo "mode=production" > /srv/demo/config/settings.conf

The minimal fix for the CONFIRMED cause — not a broader "reinstall everything" overcorrection.

VALIDATE

$ /srv/demo/start.sh
Started with config: mode=production

The original symptom is gone, confirmed with real output, not assumption.

PREVENT RECURRENCE

A real prevention step here: the script should probably check for and create its config directory on first run, or the deployment process should ensure the config exists before the service ever starts — naming this explicitly is what separates a real fix from a lucky one.

Instructor Notes

Demo goal: Show all seven steps applied in strict order to one concrete, realistic failure — the exact structure this module's Lab requires students to repeat themselves.

Approximate timing: 10 minutes live.

Common mistake to watch for: skipping straight to REPAIR (creating the file) without first articulating the hypothesis and testing it — even when the fix seems obvious, naming the hypothesis explicitly is the habit this module is building.

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